Oxidized low-density lipoprotein inhibits acetylcholine-induced vasorelaxation and increases 5-HT-induced vasoconstriction in isolated human saphenous vein.
The present study determined the vasomotor effects of oxidized low-density lipoprotein (ox-LDL) in human saphenous veins and determined whether decreased availability of L-arginine was responsible for the impaired endothelial function. Human saphenous veins were obtained from white males undergoing coronary bypass surgery. We examined the effects of ox-LDL on ACh-induced endothelium-dependent relaxation, sodium nitroprusside-induced endothelium-independent relaxation and 5-HT-induced contraction. ACh-induced vasorelaxation in the presence of L-arginine and ox-LDL was also examined. In addition, we assessed the endothelial influence on the contractile response to 5-HT. ox-LDL significantly inhibited ACh-induced relaxation but did not affect sodium nitroprusside-induced relaxation. L-Arginine pretreatment did not prevent ox-LDL-induced impairment of the relaxation response to ACh. ox-LDL significantly potentiated 5-HT-induced contraction at concentrations between 3 x 10(-6) M and 10(-4) M, an effect that was endothelium-dependent. Denudation of endothelium also significantly enhanced the contractile response to 5-HT. These data suggest that ox-LDL impairs ACh-induced endothelium-dependent relaxation and enhances 5-HT-induced endothelium-dependent contraction in human saphenous vein. L-Arginine deficiency is not responsible for the endothelial dysfunction induced by ox-LDL in human saphenous vein.
Zhao
L
L
College of Pharmacy, University of Georgia, Athens, Georgia 30602-2356, USA.
Tackett
R L
RL
D000109:Acetylcholine / Q000494:pharmacology*; D000328:Adult; D001120:Arginine / Q000502:physiology; D004730:Endothelium, Vascular / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008297:Male; D012501:Saphenous Vein; D012701:Serotonin / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects*; D014666:Vasomotor System / Q000187:drug effects*
D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; D012701:Serotonin; D001120:Arginine; D000109:Acetylcholine